What is the optical purity of a partially racemized product is the calculated specific rotation is -8◦ and the pure enantiomer has a specific rotation of -10◦? Calculate the percentage of each of the enantiomers in the partially racemized product.
I'm very lost. Is this correct?
%ee = -8/-10 x100% =80%
100-80= 20
20/2= 10%
90% (-) enantiomer
10% (+) enantiomer
1*2
im lost tooo0
To calculate the percentage of each enantiomer in the partially racemized product, you can use the formula:
% ee = (observed specific rotation / specific rotation of pure enantiomer) x 100%
Based on the given information:
- Observed specific rotation = -8°
- Specific rotation of pure enantiomer = -10°
Plugging these values into the formula:
% ee = (-8 / -10) x 100% = 80%
Now, to determine the percentages of the (+) and (-) enantiomers in the partially racemized product, you can divide the % ee by 2:
80% / 2 = 40%
Since the % ee is based on the (-) enantiomer, the (% ee / 2) represents the percentage of each enantiomer.
Therefore, the percentages of the enantiomers in the partially racemized product are:
(-) enantiomer: 40%
(+) enantiomer: 40%
To calculate the optical purity of a partially racemized product, you need to compare the observed specific rotation with the specific rotation of the pure enantiomer.
First, calculate the enantiomeric excess (ee) using the formula:
%ee = (observed specific rotation / pure enantiomer specific rotation) x 100
In this case:
%ee = (-8 / -10) x 100 = 80%
The enantiomeric excess tells you the percentage of the excess of one enantiomer over the other in the mixture.
Next, calculate the percentage of each enantiomer in the partially racemized product:
- The enantiomer with the higher specific rotation is the excess enantiomer, so it will have a percentage equal to %ee. In this case, it would be 80%.
- The enantiomer with the lower specific rotation will have a percentage equal to the complement of %ee. So, 100% - 80% = 20%. Then divide this by 2 to get the percentage of each enantiomer, since you have only two enantiomers. In this case, it would be 10%.
So, the calculation you proposed is correct:
- 90% (-) enantiomer
- 10% (+) enantiomer